Venezuela’s President Hugo Chavez is confronting “new complications” due to a respiratory infection nearly three weeks after undergoing cancer surgery.

CARACAS, Venezuela — President Hugo Chavez’s new complications after cancer surgery prompted his closest allies to call for Venezuelans to pray for him on Monday, presenting an increasingly bleak outlook and prompting growing speculation about whether the ailing leader has much longer to live.

Vice President Nicolas Maduro looked weary and spoke with a solemn expression as he announced in a televised address from Havana on Sunday that Chavez now confronts “new complications” due to a respiratory infection nearly three weeks after his operation. He described Chavez’s condition as delicate.

The streets of Caracas were abuzz on Monday with talk of Chavez’s increasingly tough fight, while the news topped the front pages of the country’s newspapers.

“He’s history now,” said Cesar Amaro, a street vendor selling newspapers and snacks at a kiosk in downtown Caracas. He motioned to a newspaper showing side-by-side photos of Maduro and National Assembly President Diosdado Cabello, and said politics will now turn to them.

Amaro said he expects a new election soon to replace Chavez. “For an illness like the one the president has, his days are numbered now,” he said matter-of-factly.

A government-organized New Year’s Eve concert had been planned in a downtown Caracas plaza featuring popular Venezuelan bands, but was canceled due to Chavez’s condition.

The president’s aides sang and prayed at a televised Mass held at the presidential palace, while Chavez’s allies urged Venezuelans to keep their president in their prayers.

“Everything suggests Chavez’s health situation hasn’t evolved as hoped,” Sucre said. He said Maduro likely remained in Havana to keep close watch on how Chavez’s condition develops.

“These hours should be key to having a more definitive prognosis of Chavez’s health, and as a consequence make the corresponding political decisions according to the constitution,” Sucre said.

Sucre and other Venezuelans said it seems increasingly unlikely that Chavez would be able to be sworn in as scheduled on Jan. 10.

The Venezuelan leader has not been seen or heard from since undergoing his fourth cancer-related surgery Dec. 11, and government officials have said he might not return in time for his inauguration for a new six-year term.

If Chavez dies or is unable to continue in office, the Venezuelan Constitution says that a new election should be held within 30 days.

Before his operation, Chavez acknowledged he faced risks and designated Maduro as his successor, telling supporters they should vote for the vice president if a new presidential election were necessary.

Chavez said at the time that his cancer had come back despite previous surgeries, chemotherapy and radiation treatment. He has been fighting an undisclosed type of pelvic cancer since June 2011.

Maduro said on Sunday that he had met with Chavez. “We greeted each other and he himself referred to these complications,” Maduro said, reading from a prepared statement.

“The president gave us precise instructions so that, after finishing the visit, we would tell the (Venezuelan) people about his current health condition,” Maduro said. “President Chavez’s state of health continues to be delicate, with complications that are being attended to, in a process not without risks.”

Maduro was seated alongside Chavez’s eldest daughter, Rosa, and son-in-law Jorge Arreaza, as well as Attorney General Cilia Flores. He held up a copy of a newspaper confirming that his message was recorded on Sunday.

“Thanks to his physical and spiritual strength, Comandante Chavez is facing this difficult situation,” Maduro said.

Maduro said he had met various times with Chavez’s medical team and relatives. He said he would remain in Havana “for the coming hours” but didn’t specify how long.

Maduro, who arrived in Havana on Saturday for the sudden and unexpected trip, is the highest-ranking Venezuelan official to see Chavez since the surgery in Cuba, where the president’s mentor Fidel Castro has reportedly made regular visits to check on him.

Before flying to Cuba, Maduro said that Energy Minister Hector Navarro would be in charge of government affairs in the meantime.

“The situation does not look good. The fact that Maduro himself would go to Cuba, leaving Hector Navarro in charge only seems understandable if Chavez’s health is precarious,” said David Smilde, a University of Georgia sociologist and analyst for the Washington Office on Latin America think tank.

Smilde said that Maduro probably made the trip “to be able to talk to Chavez himself and perhaps to talk to the Castros and other Cuban advisers about how to navigate the possibility of Chavez not being able to be sworn in on Jan. 10.”

“Mentioning twice in his nationally televised speech that Chavez has suffered new complications only reinforces the appearance that the situation is serious,” Smilde said.

Medical experts say that it’s common for patients who have undergone major surgeries to suffer respiratory infections and that how a patient fares can vary widely from a quick recovery in a couple of days to a fight for life on a respirator.

Maduro’s latest update differed markedly from a week ago, when he had said he received a phone call from the president and that Chavez was up and walking.

The vice president spoke on Sunday below a picture of 19th century independence hero Simon Bolivar, the inspiration of Chavez’s leftist Bolivarian Revolution movement.

Maduro said that Chavez had sent year-end greetings to his homeland and a “warm hug to the boys and girls of Venezuela.”

The vice president expressed faith that Chavez would “successfully fight this new battle.” He concluded his message saying: “Long live Chavez.”

On the streets of Caracas, images of Chavez smiling and saluting are emblazoned on campaign signs and murals. One newly painted mural reads: “Be strong, Chavez.”

State television played video of Chavez campaigning for re-election, including a speech when he shouted: “I am a nation!”

A new government sign atop a high-rise apartment complex reads: “YOU ALSO ARE CHAVEZ.”

Chavez has been in office since 1999 and was re-elected in October, three months after he had announced that his latest tests showed he was cancer-free.

Opposition politicians have criticized a lack of detailed information about Chavez’s condition, and last week repeated their demands for a full medical report.

Information Minister Ernesto Villegas defended the government’s handling of the situation, saying during a televised panel discussion on Sunday night that Chavez “has told the truth in his worst moments” throughout his presidency.

He also referred to a new surge of rumors about Chavez’s condition and called for respect for the president and his family.

Chavez’s daughter Maria, who has been with the president since his surgery, said in a message on her Twitter account: “Thank you people of Venezuela. Thank you people of the world. You and your love have always been our greatest strength! God is with us! We love you!”

Allies of the president also responded on Twitter, repeating the phrase: “Chavez lives and will triumph.”